System and method for volumetric reduction of medical textile and waste material

ABSTRACT

Embodiments of system and method of sanitizing medical waste are described. In one embodiment, there is a the method including, introducing the medical waste into a heating zone, heating the medical waste to a sanitizing temperature thereby melting a majority of the medial waste, moving the medical waste via gravity into a cooling receiver, cooling the medical waste by cooling the cooling receiver; and removing the medical waste from the cooling receiver.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of UK patent application serial number 1306653.5, filed on Apr. 12, 2013, the disclosure of which is incorporated herein by reference for all purposes.

TECHNICAL FIELD

The invention relates in general waste reduction, and in particular to an system and method for volumetric reduction of medical waste material.

BACKGROUND INFORMATION

Disposable synthetic polymeric textile materials are used particularly in hospital operating rooms as a sterile cover to protect patients and instruments from contamination and cross infection. Generically the material is known as sterile wrap or “Blue Wrap” and is available in many proprietary brands such as “Kimguard™” manufactured by the Kimberly Clark Corporation, and “DuraBlue™” manufactured by Cardinal Health.

The material is generally manufactured from non-woven synthetic polymers such as polypropylene or polyethylene and has the advantage of being tough and difficult to tear, non-absorbent, easy to manufacture in different sizes and is supplied as a sterile product. The material can also be manufactured to allow a predetermined air flow through the material when it is desirable to do so. Typically the material is manufactured from 100% polypropylene with a SMS (spunbond-meltblown-spunbond) structure.

The disposable material offers many financial advantages over traditional textiles which necessitate high energy costs to launder them, together with the use of potable water and chemicals such as detergents which can pollute downstream water courses. After use the material is categorized as either inert waste or bio hazardous waste and is usually disposed of by either incineration or landfill. It is estimated that globally 7000 tons of such material is destroyed daily after a single use. This material is potentially a valuable resource for recycling but issues in respect of sanitation and high volume to weight ratios make transportation expensive.

Mechanical compaction machines or balers have been used to try and reduce the volume of the material for transportation but these are not efficient as the material exhibits “memory” and re-expands after compression, the machines are slow and labor intensive to operate and the material still requires handling as bio hazardous material.

What is needed is a method of sterilization and reducing the volume of the material. Volumetric reduction and sterilization of the material would allow the material to be transported without expensive specialist waste handling techniques to a recycling facility. Additionally, the material can be recycled into other useful products. If not, the material may be significantly volumetrically reduced or densified to considerably reduce the energy cost and environmental impact of transporting the material for any other method of disposal.

SUMMARY

In response to these and other problems, in one embodiment, certain aspects of the present invention provide a method and system to both volumetrically reduce polymeric textile material and also polypropylene at the point of its use and to sterilize it.

According to certain aspects of the present invention, there is a thermal compacting system for thermally compacting medical waste, such as a polymeric textile material and/or polypropylene comprising a first and second heated surface inclined downwardly towards each other and provided with a passage at their lower ends through which melted synthetic textile material may drain.

Certain aspects of this disclosure describes a beneficially a polymeric textile and polypropylene thermal compacting system.

Such an system is beneficial as waste synthetic polymeric textile material and polypropylene can be thermally compacted at source and will include materials, for example, to include sterilized sheets in various sizes, clothing and uniforms, bedside and window curtains, cleaning cloths, instrument pouches and any other product manufactured of synthetic polymeric textile material, and other products such as polypropylene saline bags or bottles. This provides a significant benefit of providing a volumetrically reduced and sterilized product that can be recycled and also significantly reduces transportation costs associated with a high volume product. The system is also suitable for thermally compacting and sterilizing other polypropylene products such as saline bags or bottles.

The first heated surface is beneficially inclined at less than 45 degrees to a vertical axis, and preferably the second heated surface is inclined at less than 45 degrees to a vertical axis. Increasing the incline of the first and preferably second heated surface resulted in improved flow of the melted product.

The first heated surface is beneficially inclined to a vertical axis of between 25 degrees and less than 45 degrees, and preferably wherein the second heated surface is inclined to the vertical axis between 25 degrees and less than 45 degrees.

The first and preferably the second heated surfaces are beneficially arranged to be heated to a temperature in the range 250 C to 310 C, and more preferably between 275 C and 295 C and even more preferably at substantially 285 C. The first and preferably second heated surfaces include at least one heating element. Utilizing the claimed temperature ranges also ensures sterilization of the material. During the process of converting the material from a solid to a liquid the temperatures utilized have been found to destroy biological pathogens. This is assisted by the fact that during the process the material flows into a receiver as defined below that keeps the material at a raised temperature such as 260 degrees C. for 30 minutes. “Dry heat” is not always successful in sterilization and the presently claimed system and process can be considered to provide “conductive wet” heat. Unlike conventional plastic injection molding, vacuum forming or extrusion processes which are commonly used to melt and mould polypropylene materials, the process temperature of the invention has been determined to fall within the claimed temperature range. This is because the other conventional methods of melting and forming the material utilize not only heat but pressure such as a mechanical screw or a vacuum to assist in processing.

Unlike conventional equipment, aspects of the present invention does not require pressure but relies on gravity to feed the machine so the melting temperature is crucial as too low a temperature inhibits the process and too high a temperature can damage the melt index of the material making it unsuitable for recycling or in severe instances it could create a combustion risk. The temperature range is beneficially controlled by maintaining power to the heater plates on demand via contactors or solid state relays which switch on power as a result of a programmable logic controller or temperature controller sensing the set operating temperature via, for example, thermocouple sensors which are positioned inside the body of the material that provides the heated surface(s). The heated surfaces are each beneficially provided by aluminum plate heaters having at least one heating element therein. The heating element may be an electric resistance heater for example.

The temperature profile of the first and preferably the second heated surfaces may increase towards the passage. At least one heating element in the first and preferably the second heated surfaces is beneficially configured such that the temperature profile of the first and preferably second heated surfaces increases towards the passage. This further improves in melting and transfer of the material towards the passage. The temperature range of the first and beneficially second heated surface changes between substantially 295 C at a leading edge to substantially 275 C at an edge adjacent the channel.

The first and second heated surfaces beneficially define a heating zone there between. A further problem is that on leaving the heated zone and flowing through the passage the material had a propensity to solidify and as a consequence create solidified pillars of material between the heated surfaces and the receiver which created a blockage and stopped the removal of the receiver from the machine. Furthermore, at the end of a melting cycle when the heated surfaces were cooling and the heating elements isolated from power, residual amounts of material were left on the heated surfaces as the heated surfaces, preferably aluminum plates, cooled quickly.

A lower end(s) of the first and preferably second heated surfaces beneficially includes an insulating material for reducing the rate of cooling of the first and preferably second heated surfaces. The insulating material is beneficially provided applied to the heated plate and is beneficially provided on the heated plate out of or away from the flowpath of the material. This encourages material to vacate the plates and to exploit residual latent heat. A layer of micro-porous insulation is beneficially utilized. It is preferably applied to the rear of the two main plate heaters to assist the final moments of the process.

A receiver is beneficially disposed for receipt of melted synthetic textile material from the passage. A heating element is beneficially provided configured to supply heat to the receiver. The receiver is beneficially heated in order that the material flows onto a heated surface and does not immediately solidify. This ensures flow of the material, and also provides a dwell time for the material to ensure sterilization. The dwell time may be for example between 15-60 minutes for example with a preferred dwell time being 30 minutes. The temperature may be at approximately 260 degrees C. The heating element beneficially comprises a heating plate. The receiver is beneficially removably mounted with respect to the heating plate. A cooling arrangement is beneficially provided for cooling the receiver. The heating element and cooling arrangement beneficially provide a changeable heating and cooling surface for heating or cooling the receiver as appropriate. The receiver beneficially takes the form of a tray. Even more beneficially, the receiver is in the form of a mold receptacle.

After a predetermined period of time and temperature the heating elements in the machine are isolated and cool down to allow the solidification of the material and its removal from the machine. In certain applications such as large teaching hospitals with several operating rooms, the throughput of the machine would be insufficient to cope with demand as a result of the time it takes to cool the liquefied material. Accordingly, a heated plate may be provided under the receiver which would also contain cooling circuits which would be operated at the end of the heating cycle to accelerate the cooling time of the machine.

The first and preferably the second heated surfaces are preferably defined by first and preferably second heating plates respectively. The first and preferably second heating plates may be formed of aluminum which is preferably cast. The plates beneficially incorporate at least one heating element therein. The heating elements are beneficially electrically heated.

The first and preferably the second heated surfaces are beneficially formed with a non-stick coating thereon to assist transfer of material there over. A suitable coating is, for example, Teflon®.

A monitoring and recording arrangement is beneficially provided for monitoring and recording first and preferably second heated surface temperatures and preferably dwell time of melted material transferred through the passage to the receiver. This is beneficial to ensure that the material is sterile and has been processed at a sufficiently high temperature and dwell time to ensure complete sterility of the processed material.

An exhaust arrangement is beneficially provided for removing gases from the process.

A door lock is beneficially provided configured such that the door to the apparatus cannot be opened until the temperature within the apparatus has dropped to a safe level. Accordingly, the apparatus comprises a door which is beneficially electrically operated. A sensor within the apparatus is arranged to measure the temperature within the apparatus. It is beneficially provided with a control arrangement which controls the door lock. The controller arrangement beneficially includes a monitoring and recording arrangement which may transmit data to a networked device.

Also according to the present invention there is a method of thermally compacting polymeric textile materials and/or polypropylene comprising the steps of introducing polymeric textile material and/or polypropylene into a heating zone defined between first and second heated surfaces inclined downwardly towards each other and being provided at their lower ends with a passage through which polymeric synthetic textile material and/or polypropylene may drain.

These and other features, and advantages, will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. It is important to note the drawings are not intended to represent the only aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of an apparatus according to an exemplary embodiment of the present invention.

FIG. 2 a is a schematic cross-sectional plan view of a heated plate according to an exemplary embodiment of the present invention.

FIG. 2 b is a schematic cross-sectional view of an end of the heated plate.

FIG. 3 is a schematic cross-sectional plan view of a heating and cooling plate for the receiver for use in an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present inventions, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the inventions as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

When directions, such as upper, lower, top, bottom, clockwise, counter-clockwise, are discussed in this disclosure, such directions are meant to only supply reference directions for the illustrated figures and for orientation of components in the figures. The directions should not be read to imply actual directions used in any resulting invention or actual use. Under no circumstances, should such directions be read to limit or impart any meaning into the claims.

Referring to FIG. 1 there is an exemplary embodiment of certain aspects of the present invention. The apparatus is shown without a door which is closed during use and hides the internal component provided within the housing 2 and provides a seal for when the apparatus is in use. The apparatus includes first and second heated plates 4, 6 which may be beneficially formed from cast aluminum and may be electrically heated within the housing 2. The housing 2 defines an opening 8 in its front. The first and second plates 4, 6 are inclined downwardly configured to funnel waste synthetic polymeric textile material downwardly toward a channel 10 provided between the lower ends of the plates 4, 6. The waste material is therefore input into the housing 8 through the front opening, however, it is envisaged that one or more openings may be provided in another portion of the housing 2 such as in the top or in the side of the housing but beneficially above the first and second plates 4, 6.

In the examples shown the first and second plates have identical angles relative to the vertical axis. It will be appreciated, however, that the angle of the first and second plates may vary there between. The incline angle of the heated surfaces to the vertical is beneficially less than 45 degrees, and is beneficially in the range 25 degrees to less than 45 degrees. This is to ensure that the material melts and collapses and subsequently flows through the channel 10.

The first and second plates 4, 6 may be beneficially coated with Teflon®. A receiver 12 is provided supported below the channel 10 arranged to collect melted material therefrom. The receiver 12 removably seats into a docking zone 14 which is provided to ensure alignment of the receiver 12 with the channel 10. The receiver 12 seats onto a plate 16. The plate is beneficially arranged to be heated and includes one or more heating element therein, preferably of the type of electrically resistive heating elements. The plate 16 may also include one or more cooling circuits comprising a channel to transfer coolant there through for increasing speed of material processing. The plate 16 also includes a thermocouple to monitor the temperature of the plate 16.

Thermocouples are also provided on the heated plates 4, 6 to monitor temperature. Thermocouples have been identified by reference numeral 18. Temperature information from the thermocouples 18 is transferred to a controller 20. The controller 20 includes a control panel and serves to control the electrical supply to the heating elements within the heated plates 4, 6 and the plate 16. The controller controls the time of heating of the heated plates 4, 6 and the plate 16 and also controls actuation of the cooling circuit in the plate 16. The controller also provides control to an extraction arrangement 22 which includes a filtration cabinet for transfer of gases from the apparatus through an inlet 24, through a filtration cabinet 26 and out of an exhaust 28. Material leaving the heated zone defined between the heated plates 4, 6 and flowing into the receiver 12 has a propensity to solidify and as a consequence creates solidified pillars of material between the heated plates 4, 6 and the receiver 12 which can create a blockage and stop the removal of the receiver from the apparatus. Furthermore, at the end of a melting cycle when the electrical plates were isolated from power, residual amounts of material may be left on the plate heaters as the aluminum cools quickly. To encourage material to vacate the plates and to exploit residual latent heat, a layer of micro-porous insulation may be applied to the rear of the two main plate heaters to assist the final moments of the process. The PTFE coating also assisted the process by sealing the porous surface of the aluminum electrical heat plate heaters which enhanced the material's passage or slip factor as it did not permeate into the surface of the plate heaters when fluid. The PTFE's melting temperature is typically 326 C but the operating temperature of the Teflon® during the heating process is less than 200 C making it suitable for purpose in respect of health and safety issues.

It is further improved by the provision of the heated plate 16. It is preferred that the temperature of the heated plate 16 is set to be approximately 20 C lower than the set point of the heated plates 4, 6 for instance, 265 C.

After a predetermined period of time and temperature the heating elements in the machine are isolated and cool down to allow the solidification of the material and its removal from the machine. This is following a material dwell time within the receiver where heat is supplied ensuring sterilization of the material.

It has been determined that in certain applications such as large teaching hospitals with several operating rooms, the throughput of the machine would be insufficient to cope with demand as a result of the time it takes to cool the liquefied material. In this situation it is intended that the heated plate under the removable receiver would also contain cooling circuits which would be operated at the end of the heating cycle to accelerate the cooling time of the machine.

It has also been determined that the assisted cooling of the material after melting offered a considerable reduction in odor. The melted material does not liberate VOC's as the process can be considered a simple reversal of the original manufacturing process but as the polymer under temperature is an aromatic it is desirable to remove odors which could be unfamiliar in the workplace operating the machine. As the melting polymer is an aromatic an embodiment of the invention will utilize a variable speed exhaust fan (not shown) which will accelerate at the end of the process when the access door (not shown) is opened to reduce the emissions of odor. This fan also assists in cooling the machine at the end of the heating process and to maintain a partial vacuum in the machine to reduce the opportunity for odor to escape from the machine. The exhaust 28 from the machine is filtered through both a HEPA and activated carbon filter to reduce emissions in respect of fumes and odor.

To ensure the safety of operators that an electrical door lock may be utilized which will not allow the door to be opened during the process until the temperature of the inside of the machine has dropped to a safe level. This electrical door lock will be interlocked with the temperature control software running in the control arrangement 20 and the machine and will only open when thermocouple sensors confirm the ambient temperature inside the machine.

It is anticipated that the machine will be fitted with a telemetry devices to allow the machine operators from a distance to interrogate and log the machine cycle times and record any deviation from normal operation which may necessitate investigation or repair.

The apparatus may be manufactured from stainless steel material as it is intended to be used out of doors but alternatively could be manufactured from ordinary steel with a protective coating or even an insulated polymer such as GRP.

As the apparatus ensures sterility of the material after melting an embodiment of the invention contains a data logger to record both time and temperature to confirm that the material has been processed at a sufficiently high temperature and dwell time to ensure complete sterility of the processed material.

Referring to FIG. 2 there is a schematic plan cross-sectional view through the heated plate 4,6. The heated plate 4,6 comprises a first or upper end 30 and a lower or second end 32, where the second or lower end form one edge of the channel and the other of the first or second heated plate 4,6 forms the other edge of the channel. The lower edge 32 is beneficially chamfered as shown in FIG. 2 b. It will be appreciated from FIG. 2 a that the heating effect of the heating element 34 is greater towards the lower edge 32 as a result of increased volume of heating element toward the lower edge 32. This is provided to ensure continuous process of melt and flow of the waste material.

It was discovered from trial that although the largest manufacturer of the sterilization wrap's melting point was cited at 150 C, the heating source acted as a heat sink and consequently at this temperature the material did not flow. To achieve a temperature conducive to achieving a continual process of melting and flowing and to account for thermal lag the heat source which is preferably electrical resistance heaters have to operate to provide a heated surface temperature of between 275 C and 295 C. The optimum set point of these heated surfaces (plates) was determined to be 285 C. At this temperature the material will melt continually and the flow temperature rate is confined between 155 C and 160 C with the optimum temperature to achieve good flow rates being 156 C. At this temperature the melt index of the material is not degraded making the material suitable for recycling into new product or products.

Consequently the temperature range found to be suitable for the process is between 155 degrees C. and 160 degrees C. and this is controlled by maintaining power to the heated plates on demand via contactors or solid state relays which switch on power as a result of a programmable logic controller or temperature controller sensing the set operating temperature via thermocouple sensors which ideally are positioned inside the aluminum plate heaters near the area in which the process takes place.

The first and second plates consist of two cast aluminum electrically heated plate heaters which are Teflon® coated as described above to assist the passage of the material after melting and one mica insulated or cast aluminum plate heater 16 placed under the mold receptacle. It is anticipated that these heaters could also be simplified by welding or mechanically attaching round or square tubular mineral insulated electrical resistance elements to substantial aluminum, non-ferrous or ferrous plates which would reduce weight of the machine and the cost of casting and machining plate heaters. Non-ferrous materials are preferable to ferrous materials in the construction of the heating plates as they exhibit better thermal conductivity characteristics.

The plate 16 is identified in FIG. 3 and is a schematic cross-section through a plan view of this plate 16. An electrically heating element 40 is provided having electric terminals 42. Furthermore, a cooling circuit 44 is provided having an inlet 46 and outlet 48 to be used to increase productivity of the apparatus.

The present invention has been described by way of example only and it will be appreciated by the skilled addressee that modifications and variations may be made without departing from the scope of protection afforded by the appended claims.

Referring now to FIGS. 1 through 3, one manner of using one embodiment of the present invention will now be described. The method and apparatus will be used to both volumetrically reduce polymeric textile material and also polypropylene at the point of its use and to sterilize it. For instance, in one aspect, medical waste may be introduced into a heating zone defined between the inclined plates 4 and 6. The plates may be heated, which in turn will heat the medical waste to a sanitizing temperature when the waste is left in the zone for a predetermined time at a predetermined temperature. Additionally, the majority if not all of the medial waste will melt. As the medical waste melts it will move via gravity through the channel 10 and into the receiver 12. As described above, the receiver may be heated, which will keep the material from solidifying until the cooling process begins. Once the cooling process begins, the receiver may be cooled, which will in turn cool the medical waste. Not only is the medial waste sanitized, it also melts and then re-solidifies which reduces the volume of the medical waste. The medical waste can then be easily transported to a waste or recycling facility.

The abstract of the disclosure is provided for the sole reason of complying with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Any advantages and benefits described may not apply to all embodiments of the invention. When the word “means” is recited in a claim element, Applicant intends for the claim element to fall under 35 USC 112, paragraph 6. Often a label of one or more words precedes the word “means”. The word or words preceding the word “means” is a label intended to ease referencing of claims elements and is not intended to convey a structural limitation. Such means-plus-function claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent structures. For example, although a nail and a screw have different structures, they are equivalent structures since they both perform the function of fastening. Claims that do not use the word means are not intended to fall under 35 USC 112, paragraph 6.

The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many combinations, modifications and variations are possible in light of the above teaching. For instance, in certain embodiments, each of the above described components and features may be individually or sequentially combined with other components or features and still be within the scope of the present invention. Undescribed embodiments which have interchanged components are still within the scope of the present invention. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims. 

What is claimed is:
 1. A system for treating medical waste, the system comprising: a heating zone comprising a first and second heated surface inclined downwardly towards each other; wherein the first heated surface is inclined to a vertical axis of between 25 degrees and less than 45 degrees, and wherein the second heated surface is inclined to the vertical axis between 25 degrees and less than 45 degrees; wherein the first and the second heated surfaces are configured to be heated to a temperature in the range 275 C to 296 C; wherein the first and second heated surfaces are coated with a non-stick material; a channel defined by the lower ends of the first and second heating surfaces, wherein the heating temperature profile of the first and preferably second heated surfaces increases towards the passage; an insulator coupled to the lower end(s) of the first and second heated surfaces for reducing the rate of cooling of the first and preferably second heated surfaces; a receiver disposed below the channel, a heating element coupled to the receiver for heating the contents of the receiver; a cooling system coupled to the receiver for cooling the contents of the receiver.
 2. The system according to claim 1, wherein the first and preferably the second heated surfaces are arranged to be heated to a temperature substantially at 285 C.
 3. The system according to claim 1, wherein the first and the second heated surfaces are coupled to at least one heating element.
 4. The system according to claim 1, wherein the first and the second heating surfaces are formed of aluminum.
 5. The system according to claim 1, wherein the non-stick material is Teflon.
 6. The system according to claim 1, including a monitoring and recording controller for monitoring and recording first and preferably second heated surface temperatures and preferably dwell time of melted material transferred through the passage.
 7. A method of sanitizing medical waste, the method comprising: introducing the medical waste into a heating zone; heating the medical waste to a sanitizing temperature thereby melting a majority of the medial waste; moving the medical waste via gravity into a cooling receiver; cooling the medical waste by cooling the cooling receiver; and removing the medical waste from the cooling receiver.
 8. The method of claim 7, further comprising dwelling the medial waste in the heating zone for a predetermined time of less than 30 minutes.
 9. The method of claim 7, further comprising heating the medical waste to a temperature of 260 C.
 10. The method of claim 7, further comprising heating the medical waste in the cooling receiver to maintain fluidity of the medical waste.
 11. The method of claim 7, wherein the medical waste is partially made from the group consisting of sterile wrap, blue wrap, Kimguard™, and DuraBlue™.
 12. The method of claim 7, wherein the medical waste is partially made from the group consisting of polymeric textile material and/or polypropylene.
 13. The method of claim 7, further comprising monitoring and recording data associated with the heating zone.
 14. The method of claim 7, wherein the data comprises the group consisting of temperatures within the heating zone and dwell time of the medical waste within the heating zone.
 15. The method of claim 7, further comprising sending the data to a networked device.
 16. The method of claim 7, further comprising exhausting and filtering vapors from the heating zone.
 17. The method of claim 7, further comprising preventing access to the heating zone or the receiver for a predetermined amount of time or until the temperature in the heating zone reaches a predetermined temperature. 